mirrors/z3
3
0
Fork 0
mirror of https://github.com/Z3Prover/z3 synced 2025-08-05 10:50:24 +00:00
Code Activity

Reduce difference logic solver to min cost flow

Browse source
This commit is contained in:
Anh-Dung Phan 2013-10-25 17:42:03 -07:00
parent ebed5fa037
commit 532c345fd1
5 changed files with 152 additions and 65 deletions
Download patch file Download diff file Expand all files Collapse all files

33
src/smt/theory_diff_logic_def.h
View file

@ -1005,7 +1005,37 @@ bool theory_diff_logic<Ext>::maximize(theory_var v) {
}
verbose_stream() << "\n";);
NOT_IMPLEMENTED_YET();
return false;
// Double the number of edges in the new graph
dl_graph<GExt> g;
vector<dl_edge<GExt>> es = m_graph.get_all_edges();
dl_var offset = m_graph.get_num_edges();
for (unsigned i = 0; i < es.size(); ++i) {
dl_edge<GExt> e(es[i]);
g.enable_edge(g.add_edge(e));
g.enable_edge(g.add_edge(e.get_target() + offset, e.get_source() + offset, e.get_weight(), e.get_explanation()));
}
// Objective coefficients now become costs
vector<numeral> base_costs, aux_costs;
for (unsigned i = 0; i < m_objectives[v].size(); ++i) {
numeral cost(m_objectives[v][i].second);
base_costs.push_back(cost);
aux_costs.push_back(-cost);
}
vector<numeral> costs;
costs.append(base_costs);
costs.append(aux_costs);
network_flow<GExt> net_flow(g, costs);
bool is_optimal = net_flow.min_cost();
if (is_optimal) {
numeral objective_value;
vector<numeral> flows;
net_flow.get_optimal_solution(objective_value, flows);
m_objective_value = objective_value.get_rational();
// TODO: return the model of the optimal solution
}
return is_optimal;
}
template<typename Ext>
@ -1018,6 +1048,7 @@ theory_var theory_diff_logic<Ext>::add_objective(app* term) {
template<typename Ext>
inf_eps_rational<inf_rational> theory_diff_logic<Ext>::get_objective_value(theory_var v) {
NOT_IMPLEMENTED_YET();
inf_rational objective;
inf_eps_rational<inf_rational> val(objective);
return val;